1 /* $NetBSD: drm_mm.c,v 1.20 2022/09/01 11:48:59 riastradh Exp $ */ 2 3 /************************************************************************** 4 * 5 * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA. 6 * Copyright 2016 Intel Corporation 7 * All Rights Reserved. 8 * 9 * Permission is hereby granted, free of charge, to any person obtaining a 10 * copy of this software and associated documentation files (the 11 * "Software"), to deal in the Software without restriction, including 12 * without limitation the rights to use, copy, modify, merge, publish, 13 * distribute, sub license, and/or sell copies of the Software, and to 14 * permit persons to whom the Software is furnished to do so, subject to 15 * the following conditions: 16 * 17 * The above copyright notice and this permission notice (including the 18 * next paragraph) shall be included in all copies or substantial portions 19 * of the Software. 20 * 21 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 22 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 23 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL 24 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, 25 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR 26 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE 27 * USE OR OTHER DEALINGS IN THE SOFTWARE. 28 * 29 * 30 **************************************************************************/ 31 32 /* 33 * Generic simple memory manager implementation. Intended to be used as a base 34 * class implementation for more advanced memory managers. 35 * 36 * Note that the algorithm used is quite simple and there might be substantial 37 * performance gains if a smarter free list is implemented. Currently it is 38 * just an unordered stack of free regions. This could easily be improved if 39 * an RB-tree is used instead. At least if we expect heavy fragmentation. 40 * 41 * Aligned allocations can also see improvement. 42 * 43 * Authors: 44 * Thomas Hellstrm <thomas-at-tungstengraphics-dot-com> 45 */ 46 47 #include <sys/cdefs.h> 48 __KERNEL_RCSID(0, "$NetBSD: drm_mm.c,v 1.20 2022/09/01 11:48:59 riastradh Exp $"); 49 50 #include <linux/export.h> 51 #include <linux/interval_tree_generic.h> 52 #include <linux/seq_file.h> 53 #include <linux/slab.h> 54 #include <linux/stacktrace.h> 55 56 #include <drm/drm_mm.h> 57 58 /** 59 * DOC: Overview 60 * 61 * drm_mm provides a simple range allocator. The drivers are free to use the 62 * resource allocator from the linux core if it suits them, the upside of drm_mm 63 * is that it's in the DRM core. Which means that it's easier to extend for 64 * some of the crazier special purpose needs of gpus. 65 * 66 * The main data struct is &drm_mm, allocations are tracked in &drm_mm_node. 67 * Drivers are free to embed either of them into their own suitable 68 * datastructures. drm_mm itself will not do any memory allocations of its own, 69 * so if drivers choose not to embed nodes they need to still allocate them 70 * themselves. 71 * 72 * The range allocator also supports reservation of preallocated blocks. This is 73 * useful for taking over initial mode setting configurations from the firmware, 74 * where an object needs to be created which exactly matches the firmware's 75 * scanout target. As long as the range is still free it can be inserted anytime 76 * after the allocator is initialized, which helps with avoiding looped 77 * dependencies in the driver load sequence. 78 * 79 * drm_mm maintains a stack of most recently freed holes, which of all 80 * simplistic datastructures seems to be a fairly decent approach to clustering 81 * allocations and avoiding too much fragmentation. This means free space 82 * searches are O(num_holes). Given that all the fancy features drm_mm supports 83 * something better would be fairly complex and since gfx thrashing is a fairly 84 * steep cliff not a real concern. Removing a node again is O(1). 85 * 86 * drm_mm supports a few features: Alignment and range restrictions can be 87 * supplied. Furthermore every &drm_mm_node has a color value (which is just an 88 * opaque unsigned long) which in conjunction with a driver callback can be used 89 * to implement sophisticated placement restrictions. The i915 DRM driver uses 90 * this to implement guard pages between incompatible caching domains in the 91 * graphics TT. 92 * 93 * Two behaviors are supported for searching and allocating: bottom-up and 94 * top-down. The default is bottom-up. Top-down allocation can be used if the 95 * memory area has different restrictions, or just to reduce fragmentation. 96 * 97 * Finally iteration helpers to walk all nodes and all holes are provided as are 98 * some basic allocator dumpers for debugging. 99 * 100 * Note that this range allocator is not thread-safe, drivers need to protect 101 * modifications with their own locking. The idea behind this is that for a full 102 * memory manager additional data needs to be protected anyway, hence internal 103 * locking would be fully redundant. 104 */ 105 106 #ifdef CONFIG_DRM_DEBUG_MM 107 #include <linux/stackdepot.h> 108 109 #define STACKDEPTH 32 110 #define BUFSZ 4096 111 112 static noinline void save_stack(struct drm_mm_node *node) 113 { 114 unsigned long entries[STACKDEPTH]; 115 unsigned int n; 116 117 n = stack_trace_save(entries, ARRAY_SIZE(entries), 1); 118 119 /* May be called under spinlock, so avoid sleeping */ 120 node->stack = stack_depot_save(entries, n, GFP_NOWAIT); 121 } 122 123 static void show_leaks(struct drm_mm *mm) 124 { 125 struct drm_mm_node *node; 126 unsigned long *entries; 127 unsigned int nr_entries; 128 char *buf; 129 130 buf = kmalloc(BUFSZ, GFP_KERNEL); 131 if (!buf) 132 return; 133 134 list_for_each_entry(node, drm_mm_nodes(mm), node_list) { 135 if (!node->stack) { 136 DRM_ERROR("node [%08"PRIx64" + %08"PRIx64"]: unknown owner\n", 137 node->start, node->size); 138 continue; 139 } 140 141 nr_entries = stack_depot_fetch(node->stack, &entries); 142 stack_trace_snprint(buf, BUFSZ, entries, nr_entries, 0); 143 DRM_ERROR("node [%08"PRIx64" + %08"PRIx64"]: inserted at\n%s", 144 node->start, node->size, buf); 145 } 146 147 kfree(buf); 148 } 149 150 #undef STACKDEPTH 151 #undef BUFSZ 152 #else 153 static void save_stack(struct drm_mm_node *node) { } 154 static void show_leaks(struct drm_mm *mm) { } 155 #endif 156 157 #define START(node) ((node)->start) 158 #define LAST(node) ((node)->start + (node)->size - 1) 159 160 #ifndef __NetBSD__ 161 INTERVAL_TREE_DEFINE(struct drm_mm_node, rb, 162 u64, __subtree_last, 163 START, LAST, static inline, drm_mm_interval_tree) 164 #endif 165 166 struct drm_mm_node * 167 __drm_mm_interval_first(const struct drm_mm *mm_const, u64 start, u64 last) 168 { 169 struct drm_mm *mm = __UNCONST(mm_const); 170 #ifdef __NetBSD__ 171 struct drm_mm_node *node; 172 list_for_each_entry(node, &mm->head_node.node_list, node_list) { 173 if (start <= LAST(node) && START(node) <= last) 174 return node; 175 } 176 return &mm->head_node; 177 #else 178 return drm_mm_interval_tree_iter_first((struct rb_root_cached *)&mm->interval_tree, 179 start, last) ?: (struct drm_mm_node *)&mm->head_node; 180 #endif 181 } 182 EXPORT_SYMBOL(__drm_mm_interval_first); 183 184 #ifndef __NetBSD__ 185 static void drm_mm_interval_tree_add_node(struct drm_mm_node *hole_node, 186 struct drm_mm_node *node) 187 { 188 struct drm_mm *mm = hole_node->mm; 189 struct rb_node **link, *rb; 190 struct drm_mm_node *parent; 191 bool leftmost; 192 193 node->__subtree_last = LAST(node); 194 195 if (drm_mm_node_allocated(hole_node)) { 196 rb = &hole_node->rb; 197 while (rb) { 198 parent = rb_entry(rb, struct drm_mm_node, rb); 199 if (parent->__subtree_last >= node->__subtree_last) 200 break; 201 202 parent->__subtree_last = node->__subtree_last; 203 rb = rb_parent(rb); 204 } 205 206 rb = &hole_node->rb; 207 link = &hole_node->rb.rb_right; 208 leftmost = false; 209 } else { 210 rb = NULL; 211 link = &mm->interval_tree.rb_root.rb_node; 212 leftmost = true; 213 } 214 215 while (*link) { 216 rb = *link; 217 parent = rb_entry(rb, struct drm_mm_node, rb); 218 if (parent->__subtree_last < node->__subtree_last) 219 parent->__subtree_last = node->__subtree_last; 220 if (node->start < parent->start) { 221 link = &parent->rb.rb_left; 222 } else { 223 link = &parent->rb.rb_right; 224 leftmost = false; 225 } 226 } 227 228 rb_link_node(&node->rb, rb, link); 229 rb_insert_augmented_cached(&node->rb, &mm->interval_tree, leftmost, 230 &drm_mm_interval_tree_augment); 231 } 232 #endif 233 234 #ifdef __NetBSD__ 235 236 static int 237 compare_hole_addrs(void *cookie, const void *va, const void *vb) 238 { 239 const struct drm_mm_node *a = va, *b = vb; 240 const u64 aa = __drm_mm_hole_node_start(a); 241 const u64 ba = __drm_mm_hole_node_start(b); 242 243 KASSERTMSG((aa == ba || 244 aa + a->hole_size <= ba || 245 aa >= ba + b->hole_size), 246 "overlapping holes: [0x%"PRIx64", 0x%"PRIx64")," 247 " [0x%"PRIx64", 0x%"PRIx64")", 248 aa, aa + a->hole_size, 249 ba, ba + b->hole_size); 250 if (aa < ba) 251 return -1; 252 if (aa > ba) 253 return +1; 254 return 0; 255 } 256 257 static int 258 compare_hole_addr_key(void *cookie, const void *vn, const void *vk) 259 { 260 const struct drm_mm_node *n = vn; 261 const u64 a = __drm_mm_hole_node_start(n); 262 const u64 *k = vk; 263 264 if (a < *k) 265 return -1; 266 if (a + n->hole_size >= *k) /* allows range lookups */ 267 return +1; 268 return 0; 269 } 270 271 static const rb_tree_ops_t holes_addr_rb_ops = { 272 .rbto_compare_nodes = compare_hole_addrs, 273 .rbto_compare_key = compare_hole_addr_key, 274 .rbto_node_offset = offsetof(struct drm_mm_node, rb_hole_addr), 275 }; 276 277 #else 278 279 #define RB_INSERT(root, member, expr) do { \ 280 struct rb_node **link = &root.rb_node, *rb = NULL; \ 281 u64 x = expr(node); \ 282 while (*link) { \ 283 rb = *link; \ 284 if (x < expr(rb_entry(rb, struct drm_mm_node, member))) \ 285 link = &rb->rb_left; \ 286 else \ 287 link = &rb->rb_right; \ 288 } \ 289 rb_link_node(&node->member, rb, link); \ 290 rb_insert_color(&node->member, &root); \ 291 } while (0) 292 293 #endif 294 295 #define HOLE_SIZE(NODE) ((NODE)->hole_size) 296 #define HOLE_ADDR(NODE) (__drm_mm_hole_node_start(NODE)) 297 298 static u64 rb_to_hole_size(struct rb_node *rb) 299 { 300 return rb_entry(rb, struct drm_mm_node, rb_hole_size)->hole_size; 301 } 302 303 static int 304 compare_hole_sizes(void *cookie, const void *va, const void *vb) 305 { 306 const struct drm_mm_node *a = va, *b = vb; 307 308 if (a->hole_size > b->hole_size) 309 return -1; 310 if (a->hole_size < b->hole_size) 311 return +1; 312 return (a < b ? -1 : a > b ? +1 : 0); 313 } 314 315 static int 316 compare_hole_size_key(void *cookie, const void *vn, const void *vk) 317 { 318 const struct drm_mm_node *n = vn; 319 const u64 *k = vk; 320 321 if (n->hole_size > *k) 322 return -1; 323 if (n->hole_size < *k) 324 return +1; 325 return 0; 326 } 327 328 static const rb_tree_ops_t holes_size_rb_ops = { 329 .rbto_compare_nodes = compare_hole_sizes, 330 .rbto_compare_key = compare_hole_size_key, 331 .rbto_node_offset = offsetof(struct drm_mm_node, rb_hole_size), 332 }; 333 334 static void insert_hole_size(struct rb_root_cached *root, 335 struct drm_mm_node *node) 336 { 337 #ifdef __NetBSD__ 338 struct drm_mm_node *collision __diagused; 339 collision = rb_tree_insert_node(&root->rb_root.rbr_tree, node); 340 KASSERT(collision == node); 341 #else 342 struct rb_node **link = &root->rb_root.rb_node, *rb = NULL; 343 u64 x = node->hole_size; 344 bool first = true; 345 346 while (*link) { 347 rb = *link; 348 if (x > rb_to_hole_size(rb)) { 349 link = &rb->rb_left; 350 } else { 351 link = &rb->rb_right; 352 first = false; 353 } 354 } 355 356 rb_link_node(&node->rb_hole_size, rb, link); 357 rb_insert_color_cached(&node->rb_hole_size, root, first); 358 #endif 359 } 360 361 static void add_hole(struct drm_mm_node *node) 362 { 363 struct drm_mm *mm = node->mm; 364 365 node->hole_size = 366 __drm_mm_hole_node_end(node) - __drm_mm_hole_node_start(node); 367 DRM_MM_BUG_ON(!drm_mm_hole_follows(node)); 368 369 insert_hole_size(&mm->holes_size, node); 370 #ifdef __NetBSD__ 371 struct drm_mm_node *collision __diagused; 372 collision = rb_tree_insert_node(&mm->holes_addr.rbr_tree, node); 373 KASSERT(collision == node); 374 #else 375 RB_INSERT(mm->holes_addr, rb_hole_addr, HOLE_ADDR); 376 #endif 377 378 list_add(&node->hole_stack, &mm->hole_stack); 379 } 380 381 static void rm_hole(struct drm_mm_node *node) 382 { 383 DRM_MM_BUG_ON(!drm_mm_hole_follows(node)); 384 385 list_del(&node->hole_stack); 386 rb_erase_cached(&node->rb_hole_size, &node->mm->holes_size); 387 rb_erase(&node->rb_hole_addr, &node->mm->holes_addr); 388 node->hole_size = 0; 389 390 DRM_MM_BUG_ON(drm_mm_hole_follows(node)); 391 } 392 393 static inline struct drm_mm_node *rb_hole_size_to_node(struct rb_node *rb) 394 { 395 return rb_entry_safe(rb, struct drm_mm_node, rb_hole_size); 396 } 397 398 static inline struct drm_mm_node *rb_hole_addr_to_node(struct rb_node *rb) 399 { 400 return rb_entry_safe(rb, struct drm_mm_node, rb_hole_addr); 401 } 402 403 static inline u64 rb_hole_size(struct rb_node *rb) 404 { 405 return rb_entry(rb, struct drm_mm_node, rb_hole_size)->hole_size; 406 } 407 408 static struct drm_mm_node *best_hole(struct drm_mm *mm, u64 size) 409 { 410 #ifdef __NetBSD__ 411 struct drm_mm_node *best; 412 413 best = rb_tree_find_node_leq(&mm->holes_size.rb_root.rbr_tree, &size); 414 KASSERT(best == NULL || size <= best->hole_size); 415 416 return best; 417 #else 418 struct rb_node *rb = mm->holes_size.rb_root.rb_node; 419 struct drm_mm_node *best = NULL; 420 421 do { 422 struct drm_mm_node *node = 423 rb_entry(rb, struct drm_mm_node, rb_hole_size); 424 425 if (size <= node->hole_size) { 426 best = node; 427 rb = rb->rb_right; 428 } else { 429 rb = rb->rb_left; 430 } 431 } while (rb); 432 433 return best; 434 #endif 435 } 436 437 static struct drm_mm_node *find_hole(struct drm_mm *mm, u64 addr) 438 { 439 #ifdef __NetBSD__ 440 struct rb_node *rb = mm->holes_addr.rbr_tree.rbt_root; 441 #else 442 struct rb_node *rb = mm->holes_addr.rb_node; 443 #endif 444 struct drm_mm_node *node = NULL; 445 446 while (rb) { 447 u64 hole_start; 448 449 node = rb_hole_addr_to_node(rb); 450 hole_start = __drm_mm_hole_node_start(node); 451 452 if (addr < hole_start) 453 rb = node->rb_hole_addr.rb_left; 454 else if (addr > hole_start + node->hole_size) 455 rb = node->rb_hole_addr.rb_right; 456 else 457 break; 458 } 459 460 return node; 461 } 462 463 static struct drm_mm_node * 464 first_hole(struct drm_mm *mm, 465 u64 start, u64 end, u64 size, 466 enum drm_mm_insert_mode mode) 467 { 468 switch (mode) { 469 default: 470 case DRM_MM_INSERT_BEST: 471 return best_hole(mm, size); 472 473 case DRM_MM_INSERT_LOW: 474 return find_hole(mm, start); 475 476 case DRM_MM_INSERT_HIGH: 477 return find_hole(mm, end); 478 479 case DRM_MM_INSERT_EVICT: 480 return list_first_entry_or_null(&mm->hole_stack, 481 struct drm_mm_node, 482 hole_stack); 483 } 484 } 485 486 static struct drm_mm_node * 487 next_hole(struct drm_mm *mm, 488 struct drm_mm_node *node, 489 enum drm_mm_insert_mode mode) 490 { 491 switch (mode) { 492 default: 493 case DRM_MM_INSERT_BEST: 494 #ifdef __NetBSD__ 495 return RB_TREE_PREV(&mm->holes_size.rb_root.rbr_tree, node); 496 #else 497 return rb_hole_size_to_node(rb_prev(&node->rb_hole_size)); 498 #endif 499 500 case DRM_MM_INSERT_LOW: 501 #ifdef __NetBSD__ 502 return RB_TREE_NEXT(&mm->holes_addr.rbr_tree, node); 503 #else 504 return rb_hole_addr_to_node(rb_next(&node->rb_hole_addr)); 505 #endif 506 507 case DRM_MM_INSERT_HIGH: 508 #ifdef __NetBSD__ 509 return RB_TREE_PREV(&mm->holes_addr.rbr_tree, node); 510 #else 511 return rb_hole_addr_to_node(rb_prev(&node->rb_hole_addr)); 512 #endif 513 514 case DRM_MM_INSERT_EVICT: 515 node = list_next_entry(node, hole_stack); 516 return &node->hole_stack == &mm->hole_stack ? NULL : node; 517 } 518 } 519 520 /** 521 * drm_mm_reserve_node - insert an pre-initialized node 522 * @mm: drm_mm allocator to insert @node into 523 * @node: drm_mm_node to insert 524 * 525 * This functions inserts an already set-up &drm_mm_node into the allocator, 526 * meaning that start, size and color must be set by the caller. All other 527 * fields must be cleared to 0. This is useful to initialize the allocator with 528 * preallocated objects which must be set-up before the range allocator can be 529 * set-up, e.g. when taking over a firmware framebuffer. 530 * 531 * Returns: 532 * 0 on success, -ENOSPC if there's no hole where @node is. 533 */ 534 int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node) 535 { 536 u64 end = node->start + node->size; 537 struct drm_mm_node *hole; 538 u64 hole_start, hole_end; 539 u64 adj_start, adj_end; 540 541 end = node->start + node->size; 542 if (unlikely(end <= node->start)) 543 return -ENOSPC; 544 545 /* Find the relevant hole to add our node to */ 546 hole = find_hole(mm, node->start); 547 if (!hole) 548 return -ENOSPC; 549 550 adj_start = hole_start = __drm_mm_hole_node_start(hole); 551 adj_end = hole_end = hole_start + hole->hole_size; 552 553 if (mm->color_adjust) 554 mm->color_adjust(hole, node->color, &adj_start, &adj_end); 555 556 if (adj_start > node->start || adj_end < end) 557 return -ENOSPC; 558 559 node->mm = mm; 560 561 __set_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags); 562 list_add(&node->node_list, &hole->node_list); 563 #ifndef __NetBSD__ 564 drm_mm_interval_tree_add_node(hole, node); 565 #endif 566 node->hole_size = 0; 567 568 rm_hole(hole); 569 if (node->start > hole_start) 570 add_hole(hole); 571 if (end < hole_end) 572 add_hole(node); 573 574 save_stack(node); 575 return 0; 576 } 577 EXPORT_SYMBOL(drm_mm_reserve_node); 578 579 static u64 rb_to_hole_size_or_zero(struct rb_node *rb) 580 { 581 return rb ? rb_to_hole_size(rb) : 0; 582 } 583 584 /** 585 * drm_mm_insert_node_in_range - ranged search for space and insert @node 586 * @mm: drm_mm to allocate from 587 * @node: preallocate node to insert 588 * @size: size of the allocation 589 * @alignment: alignment of the allocation 590 * @color: opaque tag value to use for this node 591 * @range_start: start of the allowed range for this node 592 * @range_end: end of the allowed range for this node 593 * @mode: fine-tune the allocation search and placement 594 * 595 * The preallocated @node must be cleared to 0. 596 * 597 * Returns: 598 * 0 on success, -ENOSPC if there's no suitable hole. 599 */ 600 int drm_mm_insert_node_in_range(struct drm_mm * const mm, 601 struct drm_mm_node * const node, 602 u64 size, u64 alignment, 603 unsigned long color, 604 u64 range_start, u64 range_end, 605 enum drm_mm_insert_mode mode) 606 { 607 struct drm_mm_node *hole; 608 u64 remainder_mask; 609 bool once; 610 611 DRM_MM_BUG_ON(range_start > range_end); 612 613 if (unlikely(size == 0 || range_end - range_start < size)) 614 return -ENOSPC; 615 616 if (rb_to_hole_size_or_zero(rb_first_cached(&mm->holes_size)) < size) 617 return -ENOSPC; 618 619 if (alignment <= 1) 620 alignment = 0; 621 622 once = mode & DRM_MM_INSERT_ONCE; 623 mode &= ~DRM_MM_INSERT_ONCE; 624 625 remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0; 626 for (hole = first_hole(mm, range_start, range_end, size, mode); 627 hole; 628 hole = once ? NULL : next_hole(mm, hole, mode)) { 629 u64 hole_start = __drm_mm_hole_node_start(hole); 630 u64 hole_end = hole_start + hole->hole_size; 631 u64 adj_start, adj_end; 632 u64 col_start, col_end; 633 634 if (mode == DRM_MM_INSERT_LOW && hole_start >= range_end) 635 break; 636 637 if (mode == DRM_MM_INSERT_HIGH && hole_end <= range_start) 638 break; 639 640 col_start = hole_start; 641 col_end = hole_end; 642 if (mm->color_adjust) 643 mm->color_adjust(hole, color, &col_start, &col_end); 644 645 adj_start = max(col_start, range_start); 646 adj_end = min(col_end, range_end); 647 648 if (adj_end <= adj_start || adj_end - adj_start < size) 649 continue; 650 651 if (mode == DRM_MM_INSERT_HIGH) 652 adj_start = adj_end - size; 653 654 if (alignment) { 655 u64 rem; 656 657 if (likely(remainder_mask)) 658 rem = adj_start & remainder_mask; 659 else 660 div64_u64_rem(adj_start, alignment, &rem); 661 if (rem) { 662 adj_start -= rem; 663 if (mode != DRM_MM_INSERT_HIGH) 664 adj_start += alignment; 665 666 if (adj_start < max(col_start, range_start) || 667 min(col_end, range_end) - adj_start < size) 668 continue; 669 670 if (adj_end <= adj_start || 671 adj_end - adj_start < size) 672 continue; 673 } 674 } 675 676 node->mm = mm; 677 node->size = size; 678 node->start = adj_start; 679 node->color = color; 680 node->hole_size = 0; 681 682 __set_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags); 683 list_add(&node->node_list, &hole->node_list); 684 #ifndef __NetBSD__ 685 drm_mm_interval_tree_add_node(hole, node); 686 #endif 687 688 rm_hole(hole); 689 if (adj_start > hole_start) 690 add_hole(hole); 691 if (adj_start + size < hole_end) 692 add_hole(node); 693 694 save_stack(node); 695 return 0; 696 } 697 698 return -ENOSPC; 699 } 700 EXPORT_SYMBOL(drm_mm_insert_node_in_range); 701 702 static inline bool drm_mm_node_scanned_block(const struct drm_mm_node *node) 703 { 704 return test_bit(DRM_MM_NODE_SCANNED_BIT, &node->flags); 705 } 706 707 /** 708 * drm_mm_remove_node - Remove a memory node from the allocator. 709 * @node: drm_mm_node to remove 710 * 711 * This just removes a node from its drm_mm allocator. The node does not need to 712 * be cleared again before it can be re-inserted into this or any other drm_mm 713 * allocator. It is a bug to call this function on a unallocated node. 714 */ 715 void drm_mm_remove_node(struct drm_mm_node *node) 716 { 717 struct drm_mm *mm = node->mm; 718 struct drm_mm_node *prev_node; 719 720 DRM_MM_BUG_ON(!drm_mm_node_allocated(node)); 721 DRM_MM_BUG_ON(drm_mm_node_scanned_block(node)); 722 723 prev_node = list_prev_entry(node, node_list); 724 725 if (drm_mm_hole_follows(node)) 726 rm_hole(node); 727 728 #ifdef __NetBSD__ 729 __USE(mm); 730 #else 731 drm_mm_interval_tree_remove(node, &mm->interval_tree); 732 #endif 733 list_del(&node->node_list); 734 735 if (drm_mm_hole_follows(prev_node)) 736 rm_hole(prev_node); 737 add_hole(prev_node); 738 739 clear_bit_unlock(DRM_MM_NODE_ALLOCATED_BIT, &node->flags); 740 } 741 EXPORT_SYMBOL(drm_mm_remove_node); 742 743 /** 744 * drm_mm_replace_node - move an allocation from @old to @new 745 * @old: drm_mm_node to remove from the allocator 746 * @new: drm_mm_node which should inherit @old's allocation 747 * 748 * This is useful for when drivers embed the drm_mm_node structure and hence 749 * can't move allocations by reassigning pointers. It's a combination of remove 750 * and insert with the guarantee that the allocation start will match. 751 */ 752 void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new) 753 { 754 struct drm_mm *mm = old->mm; 755 756 DRM_MM_BUG_ON(!drm_mm_node_allocated(old)); 757 758 *new = *old; 759 760 __set_bit(DRM_MM_NODE_ALLOCATED_BIT, &new->flags); 761 list_replace(&old->node_list, &new->node_list); 762 #ifndef __NetBSD__ 763 rb_replace_node_cached(&old->rb, &new->rb, &mm->interval_tree); 764 #endif 765 766 if (drm_mm_hole_follows(old)) { 767 list_replace(&old->hole_stack, &new->hole_stack); 768 rb_replace_node_cached(&old->rb_hole_size, 769 &new->rb_hole_size, 770 &mm->holes_size); 771 rb_replace_node(&old->rb_hole_addr, 772 &new->rb_hole_addr, 773 &mm->holes_addr); 774 } 775 776 clear_bit_unlock(DRM_MM_NODE_ALLOCATED_BIT, &old->flags); 777 } 778 EXPORT_SYMBOL(drm_mm_replace_node); 779 780 /** 781 * DOC: lru scan roster 782 * 783 * Very often GPUs need to have continuous allocations for a given object. When 784 * evicting objects to make space for a new one it is therefore not most 785 * efficient when we simply start to select all objects from the tail of an LRU 786 * until there's a suitable hole: Especially for big objects or nodes that 787 * otherwise have special allocation constraints there's a good chance we evict 788 * lots of (smaller) objects unnecessarily. 789 * 790 * The DRM range allocator supports this use-case through the scanning 791 * interfaces. First a scan operation needs to be initialized with 792 * drm_mm_scan_init() or drm_mm_scan_init_with_range(). The driver adds 793 * objects to the roster, probably by walking an LRU list, but this can be 794 * freely implemented. Eviction candiates are added using 795 * drm_mm_scan_add_block() until a suitable hole is found or there are no 796 * further evictable objects. Eviction roster metadata is tracked in &struct 797 * drm_mm_scan. 798 * 799 * The driver must walk through all objects again in exactly the reverse 800 * order to restore the allocator state. Note that while the allocator is used 801 * in the scan mode no other operation is allowed. 802 * 803 * Finally the driver evicts all objects selected (drm_mm_scan_remove_block() 804 * reported true) in the scan, and any overlapping nodes after color adjustment 805 * (drm_mm_scan_color_evict()). Adding and removing an object is O(1), and 806 * since freeing a node is also O(1) the overall complexity is 807 * O(scanned_objects). So like the free stack which needs to be walked before a 808 * scan operation even begins this is linear in the number of objects. It 809 * doesn't seem to hurt too badly. 810 */ 811 812 /** 813 * drm_mm_scan_init_with_range - initialize range-restricted lru scanning 814 * @scan: scan state 815 * @mm: drm_mm to scan 816 * @size: size of the allocation 817 * @alignment: alignment of the allocation 818 * @color: opaque tag value to use for the allocation 819 * @start: start of the allowed range for the allocation 820 * @end: end of the allowed range for the allocation 821 * @mode: fine-tune the allocation search and placement 822 * 823 * This simply sets up the scanning routines with the parameters for the desired 824 * hole. 825 * 826 * Warning: 827 * As long as the scan list is non-empty, no other operations than 828 * adding/removing nodes to/from the scan list are allowed. 829 */ 830 void drm_mm_scan_init_with_range(struct drm_mm_scan *scan, 831 struct drm_mm *mm, 832 u64 size, 833 u64 alignment, 834 unsigned long color, 835 u64 start, 836 u64 end, 837 enum drm_mm_insert_mode mode) 838 { 839 DRM_MM_BUG_ON(start >= end); 840 DRM_MM_BUG_ON(!size || size > end - start); 841 DRM_MM_BUG_ON(mm->scan_active); 842 843 scan->mm = mm; 844 845 if (alignment <= 1) 846 alignment = 0; 847 848 scan->color = color; 849 scan->alignment = alignment; 850 scan->remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0; 851 scan->size = size; 852 scan->mode = mode; 853 854 DRM_MM_BUG_ON(end <= start); 855 scan->range_start = start; 856 scan->range_end = end; 857 858 scan->hit_start = U64_MAX; 859 scan->hit_end = 0; 860 } 861 EXPORT_SYMBOL(drm_mm_scan_init_with_range); 862 863 /** 864 * drm_mm_scan_add_block - add a node to the scan list 865 * @scan: the active drm_mm scanner 866 * @node: drm_mm_node to add 867 * 868 * Add a node to the scan list that might be freed to make space for the desired 869 * hole. 870 * 871 * Returns: 872 * True if a hole has been found, false otherwise. 873 */ 874 bool drm_mm_scan_add_block(struct drm_mm_scan *scan, 875 struct drm_mm_node *node) 876 { 877 struct drm_mm *mm = scan->mm; 878 struct drm_mm_node *hole; 879 u64 hole_start, hole_end; 880 u64 col_start, col_end; 881 u64 adj_start, adj_end; 882 883 DRM_MM_BUG_ON(node->mm != mm); 884 DRM_MM_BUG_ON(!drm_mm_node_allocated(node)); 885 DRM_MM_BUG_ON(drm_mm_node_scanned_block(node)); 886 __set_bit(DRM_MM_NODE_SCANNED_BIT, &node->flags); 887 mm->scan_active++; 888 889 /* Remove this block from the node_list so that we enlarge the hole 890 * (distance between the end of our previous node and the start of 891 * or next), without poisoning the link so that we can restore it 892 * later in drm_mm_scan_remove_block(). 893 */ 894 hole = list_prev_entry(node, node_list); 895 DRM_MM_BUG_ON(list_next_entry(hole, node_list) != node); 896 __list_del_entry(&node->node_list); 897 898 hole_start = __drm_mm_hole_node_start(hole); 899 hole_end = __drm_mm_hole_node_end(hole); 900 901 col_start = hole_start; 902 col_end = hole_end; 903 if (mm->color_adjust) 904 mm->color_adjust(hole, scan->color, &col_start, &col_end); 905 906 adj_start = max(col_start, scan->range_start); 907 adj_end = min(col_end, scan->range_end); 908 if (adj_end <= adj_start || adj_end - adj_start < scan->size) 909 return false; 910 911 if (scan->mode == DRM_MM_INSERT_HIGH) 912 adj_start = adj_end - scan->size; 913 914 if (scan->alignment) { 915 u64 rem; 916 917 if (likely(scan->remainder_mask)) 918 rem = adj_start & scan->remainder_mask; 919 else 920 div64_u64_rem(adj_start, scan->alignment, &rem); 921 if (rem) { 922 adj_start -= rem; 923 if (scan->mode != DRM_MM_INSERT_HIGH) 924 adj_start += scan->alignment; 925 if (adj_start < max(col_start, scan->range_start) || 926 min(col_end, scan->range_end) - adj_start < scan->size) 927 return false; 928 929 if (adj_end <= adj_start || 930 adj_end - adj_start < scan->size) 931 return false; 932 } 933 } 934 935 scan->hit_start = adj_start; 936 scan->hit_end = adj_start + scan->size; 937 938 DRM_MM_BUG_ON(scan->hit_start >= scan->hit_end); 939 DRM_MM_BUG_ON(scan->hit_start < hole_start); 940 DRM_MM_BUG_ON(scan->hit_end > hole_end); 941 942 return true; 943 } 944 EXPORT_SYMBOL(drm_mm_scan_add_block); 945 946 /** 947 * drm_mm_scan_remove_block - remove a node from the scan list 948 * @scan: the active drm_mm scanner 949 * @node: drm_mm_node to remove 950 * 951 * Nodes **must** be removed in exactly the reverse order from the scan list as 952 * they have been added (e.g. using list_add() as they are added and then 953 * list_for_each() over that eviction list to remove), otherwise the internal 954 * state of the memory manager will be corrupted. 955 * 956 * When the scan list is empty, the selected memory nodes can be freed. An 957 * immediately following drm_mm_insert_node_in_range_generic() or one of the 958 * simpler versions of that function with !DRM_MM_SEARCH_BEST will then return 959 * the just freed block (because it's at the top of the free_stack list). 960 * 961 * Returns: 962 * True if this block should be evicted, false otherwise. Will always 963 * return false when no hole has been found. 964 */ 965 bool drm_mm_scan_remove_block(struct drm_mm_scan *scan, 966 struct drm_mm_node *node) 967 { 968 struct drm_mm_node *prev_node; 969 970 DRM_MM_BUG_ON(node->mm != scan->mm); 971 DRM_MM_BUG_ON(!drm_mm_node_scanned_block(node)); 972 __clear_bit(DRM_MM_NODE_SCANNED_BIT, &node->flags); 973 974 DRM_MM_BUG_ON(!node->mm->scan_active); 975 node->mm->scan_active--; 976 977 /* During drm_mm_scan_add_block() we decoupled this node leaving 978 * its pointers intact. Now that the caller is walking back along 979 * the eviction list we can restore this block into its rightful 980 * place on the full node_list. To confirm that the caller is walking 981 * backwards correctly we check that prev_node->next == node->next, 982 * i.e. both believe the same node should be on the other side of the 983 * hole. 984 */ 985 prev_node = list_prev_entry(node, node_list); 986 DRM_MM_BUG_ON(list_next_entry(prev_node, node_list) != 987 list_next_entry(node, node_list)); 988 list_add(&node->node_list, &prev_node->node_list); 989 990 return (node->start + node->size > scan->hit_start && 991 node->start < scan->hit_end); 992 } 993 EXPORT_SYMBOL(drm_mm_scan_remove_block); 994 995 /** 996 * drm_mm_scan_color_evict - evict overlapping nodes on either side of hole 997 * @scan: drm_mm scan with target hole 998 * 999 * After completing an eviction scan and removing the selected nodes, we may 1000 * need to remove a few more nodes from either side of the target hole if 1001 * mm.color_adjust is being used. 1002 * 1003 * Returns: 1004 * A node to evict, or NULL if there are no overlapping nodes. 1005 */ 1006 struct drm_mm_node *drm_mm_scan_color_evict(struct drm_mm_scan *scan) 1007 { 1008 struct drm_mm *mm = scan->mm; 1009 struct drm_mm_node *hole; 1010 u64 hole_start, hole_end; 1011 1012 DRM_MM_BUG_ON(list_empty(&mm->hole_stack)); 1013 1014 if (!mm->color_adjust) 1015 return NULL; 1016 1017 /* 1018 * The hole found during scanning should ideally be the first element 1019 * in the hole_stack list, but due to side-effects in the driver it 1020 * may not be. 1021 */ 1022 list_for_each_entry(hole, &mm->hole_stack, hole_stack) { 1023 hole_start = __drm_mm_hole_node_start(hole); 1024 hole_end = hole_start + hole->hole_size; 1025 1026 if (hole_start <= scan->hit_start && 1027 hole_end >= scan->hit_end) 1028 break; 1029 } 1030 1031 /* We should only be called after we found the hole previously */ 1032 DRM_MM_BUG_ON(&hole->hole_stack == &mm->hole_stack); 1033 if (unlikely(&hole->hole_stack == &mm->hole_stack)) 1034 return NULL; 1035 1036 DRM_MM_BUG_ON(hole_start > scan->hit_start); 1037 DRM_MM_BUG_ON(hole_end < scan->hit_end); 1038 1039 mm->color_adjust(hole, scan->color, &hole_start, &hole_end); 1040 if (hole_start > scan->hit_start) 1041 return hole; 1042 if (hole_end < scan->hit_end) 1043 return list_next_entry(hole, node_list); 1044 1045 return NULL; 1046 } 1047 EXPORT_SYMBOL(drm_mm_scan_color_evict); 1048 1049 /** 1050 * drm_mm_init - initialize a drm-mm allocator 1051 * @mm: the drm_mm structure to initialize 1052 * @start: start of the range managed by @mm 1053 * @size: end of the range managed by @mm 1054 * 1055 * Note that @mm must be cleared to 0 before calling this function. 1056 */ 1057 void drm_mm_init(struct drm_mm *mm, u64 start, u64 size) 1058 { 1059 DRM_MM_BUG_ON(start + size <= start); 1060 1061 mm->color_adjust = NULL; 1062 1063 INIT_LIST_HEAD(&mm->hole_stack); 1064 #ifdef __NetBSD__ 1065 /* XXX interval tree */ 1066 rb_tree_init(&mm->holes_size.rb_root.rbr_tree, &holes_size_rb_ops); 1067 rb_tree_init(&mm->holes_addr.rbr_tree, &holes_addr_rb_ops); 1068 #else 1069 mm->interval_tree = RB_ROOT_CACHED; 1070 mm->holes_size = RB_ROOT_CACHED; 1071 mm->holes_addr = RB_ROOT; 1072 #endif 1073 1074 /* Clever trick to avoid a special case in the free hole tracking. */ 1075 INIT_LIST_HEAD(&mm->head_node.node_list); 1076 mm->head_node.flags = 0; 1077 mm->head_node.mm = mm; 1078 mm->head_node.start = start + size; 1079 mm->head_node.size = -size; 1080 add_hole(&mm->head_node); 1081 1082 mm->scan_active = 0; 1083 } 1084 EXPORT_SYMBOL(drm_mm_init); 1085 1086 /** 1087 * drm_mm_takedown - clean up a drm_mm allocator 1088 * @mm: drm_mm allocator to clean up 1089 * 1090 * Note that it is a bug to call this function on an allocator which is not 1091 * clean. 1092 */ 1093 void drm_mm_takedown(struct drm_mm *mm) 1094 { 1095 if (WARN(!drm_mm_clean(mm), 1096 "Memory manager not clean during takedown.\n")) 1097 show_leaks(mm); 1098 } 1099 EXPORT_SYMBOL(drm_mm_takedown); 1100 1101 static u64 drm_mm_dump_hole(struct drm_printer *p, const struct drm_mm_node *entry) 1102 { 1103 u64 start, size; 1104 1105 size = entry->hole_size; 1106 if (size) { 1107 start = drm_mm_hole_node_start(entry); 1108 drm_printf(p, "%#018"PRIx64"-%#018"PRIx64": %"PRIu64": free\n", 1109 start, start + size, size); 1110 } 1111 1112 return size; 1113 } 1114 /** 1115 * drm_mm_print - print allocator state 1116 * @mm: drm_mm allocator to print 1117 * @p: DRM printer to use 1118 */ 1119 void drm_mm_print(const struct drm_mm *mm, struct drm_printer *p) 1120 { 1121 const struct drm_mm_node *entry; 1122 u64 total_used = 0, total_free = 0, total = 0; 1123 1124 total_free += drm_mm_dump_hole(p, &mm->head_node); 1125 1126 drm_mm_for_each_node(entry, mm) { 1127 drm_printf(p, "%#018"PRIx64"-%#018"PRIx64": %"PRIu64": used\n", entry->start, 1128 entry->start + entry->size, entry->size); 1129 total_used += entry->size; 1130 total_free += drm_mm_dump_hole(p, entry); 1131 } 1132 total = total_free + total_used; 1133 1134 drm_printf(p, "total: %"PRIu64", used %"PRIu64" free %"PRIu64"\n", total, 1135 total_used, total_free); 1136 } 1137 EXPORT_SYMBOL(drm_mm_print); 1138
Indexes created Sat Sep 20 22:09:52 GMT 2025